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The Greek Alphabet and Other Symbols

The Greek Alphabet

Johann Bayer was a celestial cartographer who compiled a star catalogue using what are now known as Bayer designations. A star's Bayer designation is a lower case Greek letter, followed by the genetive form of its parent constellation's Latin name. Under this system, the brightest star in a constellations is usually assigned the Greek letter alpha α, the next brightest star beta β and so on, but there are a number of exceptions to this rule. If there are more than 24 stars in the constellation needing a designation, lower case Latin letters (a, b, c, …, z) are used in place of lower case Greek letters. In constellations with very large number of stars, upper case Latin letters (A, B, C, …, Q) are also used. (Bayer did not use upper case letters beyond the letter Q.) Since Greek letters are not always familiar to non-scientists, a list of the alphabet is given below.

Lower Upper Letter   Lower Upper Letter   Lower Upper Letter   Lower Upper Letter
α Α alpha η Η eta ν Ν nu τ Τ tau
β Β beta θ Θ theta ξ Ξ xi υ Υ upsilon
γ Γ gamma ι Ι iota ο Ο omicron φ Φ phi
δ Δ delta κ Κ kappa π Π pi χ Χ chi
ε Ε epsilon λ Λ lambda ρ Ρ rho ψ Ψ psi
ζ Ζ zeta μ Μ mu σ Σ sigma ω Ω omega

Roman Numerals

These symbols are used to designate planetary satellites and stellar luminosity classes.

Roman Arabic   Roman Arabic   Roman Arabic   Roman Arabic   Roman Arabic
1 4 7 10 50
2 5 8 11 100
3 6 9 12 500
1000

Other Astronomical Symbols

These symbols were once commonly used by astronomers but these days they mostly appear in almanacs and horoscopes. The main exceptions are the symbols for the Sun and the Earth which are still often seen in published research and academic texts.

Sun/Moon Planets Miscellaneous Zodiac
Symbol Body Symbol Body Symbol Body Symbol Body
Sun Mercury Comet Aries
New Moon Venus Star Taurus
increscent (waxing crescent) Moon Earth Descending Node Gemini
First Quarter Moon Mars Ascending Node Cancer
Full Moon Jupiter Conjunction Leo
Last Quarter Moon Saturn Opposition Virgo
decrescent (waning crescent) Moon Uranus Quadrature Libra
Neptune Scorpius
Sagittarius
Capricornus
Aquarius
Pisces

Miscellaneous Abbreviations

Abbreviation Catalogue/Survey/Telescope/Etc.
2MASS Two-Micron All Sky Survey
BD Bonner Durchmusterung
BPS CS Beers-Preston-Shectman: Curtis Schmidt Telescope (survey for low metal abundance stars)
C Caldwell Catalogue
CD Cordoba Durchmusterung
CPD Cape Photograph Durchmusterung
Cr Collinder's Catalogue of Open Star Clusters
GI, GJ Gliese Catalogue of Nearby Stars (and supplements)
HAT Hungarian Automated Telescope
HD Henry Draper Catalogue
HIP Hipparcos Catalogue
IC Index Catalogue of Nebulae and Clusters of Stars
M Messier Catalogue
Mel Melotte Catalogue of Star Clusters
NGC New General Catalogue of Nebulae and Cluster of Stars
PSR Pulsating Source of Radio
SN Supernova
SS Stephenson-Sanduleak (catalogue of stars with strong Hα emission lines)
TrES Transatlantic Exoplanet Survey
WASP Wide Angle Search for Planets
WISE Wide-field Infrared Survey Explorer